Overflow, Part XIV

Sander Sitter

The Sander Sitter is essentially a round crepe pad in a tray, mounted on bearings.  The idea is that you set your random orbit sander down in the tray while it is running or spinning down and the crepe cleans the abrasive disc.

I no longer own a 5″ sander, so I’m giving it away.  It is in very good condition and I’ll even dust it off for the winner.

If you would like this 5″ Sander Sitter, please leave a comment below indicating your interest by noon of Thursday, August 29.  To qualify, simply state that you would like the accessory and tell me which of my creations is your favourite.

I will then draw a winner at random.  Even if you don’t get this item, remember that there is still much more I want to give away.

And if you haven’t already, be sure to subscribe to my blog so you can be notified as soon as I post something new!  Please tell your friends about my Overflow program.

Review the details of the Overflow program.

Review of the Mirka CEROS


I have had the 6″ Mirka CEROS (Compact Electric Random Orbit Sander) for about a year.  Although I have not used it in a production shop environment, I used it extensively for sanding sculptural work and, to a lesser degree, for flat surfaces.  I have had absolutely no issues with it.

When I purchased the Mirka CEROS, it was only available as a 5″ or 6″ sander with a 5 mm orbit.  The 5 mm orbit is for general work.  Since then, Mirka has released two more 6″ CEROS models – one with a 2.5 mm stroke for finish sanding and one with an 8 mm stroke for more aggressive sanding.  I do not believe these are currently available in North America.

Mirka CEROS in Systainer


The sanding action is very smooth and the DC motor is powerful and reasonably quiet (68 dB, which is similar to a piano practice).  It is lightweight and well-balanced, making it comfortable to use with either one hand or two.  The power cord is quite flexible and permanently attached to the sander.  Mirka sells a hose for the sanders, which is more flexible and lighter (for improved ergonomics) than the Festool Anti-Static D27 hose.  The Mirka CEROS has a round dust port with female threads to accept a 1-1/4″ diameter threaded hose.

Although the Mirka sanders closely resemble pneumatic ones, they are powered by a maintenance-free, brushless DC motor and do not require a large air compressor.  The sanders have a 14′-long power cord that plugs into one end of a 8-1/2″ x 5-1/2″ x 3-1/4″ transformer.  A 6′-long power cord runs from the other end of the transformer into a standard AC outlet.

Mirka CEROS Package


The Mirka CEROS is available with either a 125mm (5″) or 150mm (6″) diameter pad.  The smaller sander weighs 870 grams (1.9 pounds) and the larger weighs 920 grams (2 pounds).  I think the 6″ version is more practical not only because it can sand a larger area more quickly, but because the larger pad has a greater distance between the edge of the pad and its body which is useful when working in tight quarters.

5″ and 6″ Mirka CEROSs

Speed Control

The speed of the sanding pad can be adjusted from 4,000-10,000 RPM in 1,000 RPM increments using the buttons on the top-rear of the sander.  Between the speed control buttons is a power button for safety to prevent the sander from starting accidentally.  The paddle switch on top is pressed and held down to operate the tool.  By feathering the paddle, you can control the speed as well but it is very sensitive and not a very reliable way to run the sander at a lower speed.  Instead, it functions as a soft-start feature, of sorts.

Mirka CEROS, Top View


One addition that I would like to see is a pad brake.  After releasing the paddle switch with the pad turning at 10,000 RPM, the pad continues to spin for about 19 seconds.

Video Review

This first video explains and demonstrates some of the features of the Mirka CEROS.  (Duration: 10:19.)

(Note:  Since recording this video, a reader has pointed out that the CEROS set to run at the lowest speed will indeed draw enough current when under moderate load to run a Festool Dust Extractor set to auto-start.)

In these two posts, you can read more about how I:

  1. combined the Mirka CEROS’s transformer with my Festool CT26 Dust Extractor; and
  2. modified the Festool D27 hose’s tool end to fit the Mirka CEROS’s dust collection port.

Video Demonstration

This second video is a demonstration of the Mirka CEROS.  In the first part, I sand the flat top of a bench with 80, 120, 180, 220, and 320-grit Abranet discs.  In the latter part of the video, I demonstrate how I sand contoured parts with and without the foam interface pad.  (Duration: 13:43.)


Consider this sander because it:

  1. is powerful and easy to control;
  2. runs quietly and smoothly;
  3. feels good because it is compact and well-balanced;
  4. requires very little maintenance because it has few wearing components; and
  5. does not require a large air compressor to run (as a pneumatic sander does).


The Mirka CEROS comes with a 3-year warranty.  You can download the warranty information as well as manual from the Mirka CEROS website.


Also, check out the Abranet abrasive discs made by Mirka.  The discs last a long time and don’t require alignment of any dust collection holes.  I would recommend getting the 80-, 120-, and 180-grit sanding discs as well as a Pad Saver (I called it a platen protector in the video).  If you work with non-flat surface, I would also recommend looking at the 10 mm (3/8″) Multi Interface Pads


(I do not receive any compensation for what I write and the list of suppliers is by no means an exhaustive one; I’ve simply listed some to get you started.)

Mirka Part Numbers

*Some dealers sell these parts individually.
**8295610111     150 mm (6″) 67-Hole Pad Savers, Pkg of 5 work with the 150 mm CEROS as well.

Hand-Carving Threads (to Connect a Mirka CEROS to a Festool 27mm Hose)

To see how I installed the CEROS transformer on my Festool CT26 dust extractor, click here.

This article shows how to layout and carve threads in a rubber hose end-piece.  However, the same techniques can be used to carve male threads in wood or another material.

Mirka CEROS (Photo from Ultimate Tools)

The Mirka CEROS (Compact Electric Random Orbit Sander) has a dust extraction port with internal threads that screw directly onto the end of a Festool 27mm hose to prevent it from dislodging accidentally.  However, that means the tapered rubber connector on the end of the hose needs to be removed.  This is not a difficult procedure but it is not something I want to do every time I switch between the sander and another tool.

Photo by Matthew Schenker

I know of four solutions to avoid having to install or remove the connector when using it with the CEROS:

  1. Jam the connector in and hope it stays;
  2. Buy another hose and dedicate it to the CEROS;
  3. Make an adapter using a short length of 27mm hose and some fittings; or
  4. Cut threads on the connector.
For the first few months of use, I simply jammed the connector into the dust collection port of the CEROS.  I tapered the end to make it easier to insert. However, it would pop out occasionally.  I couldn’t justify buying another hose and didn’t like the adapter.

Tired of fighting to get it to stay connected with just a press-fit, I decided to carve threads on the adapter to secure it into the port.  I used two carving tools, a rule (double square) and black electrical tape.

The first critical step was layout.  I wrapped tape around the connector, ensuring that the distance from the edge of the previous layer to that of the next layer matched the pitch of the port’s internal threads (which also matched the external threads of the 27mm hose).  I double-checked that the spacing was consistent and that I’d laid out the thread with the correct direction of rotation.

Next, I used a V-shaped carving gouge (#12 sweep, 2mm wide) along the edges of the tape to transfer the layout lines through to the connector.  Then I peeled off the tape so I could better see the V-cuts.

Following the V-cuts, I used a veining tool (#11 sweep, 3mm wide) to cut the threads.

Finally, I tried to thread the connector into the port.  When simply press fit, there was 7/8″ of exposed connector between the first shoulder and port.

Once threaded in fully, only 1/2″ of the connector was exposed between the first shoulder and port.  The threads mated very well and there was no chance of the hose disconnecting accidentally.  And I was able to still use the hose with other tools without a problem.